This chapter collects the mathematical tools needed to transform lattices without preserving isometry. The lines drawn on the sunflower, seen locally, join the nearest seed positions and they are by definition the shortest distances between those two points. Yet globally they are not straight lines but curved spirals. Conversely, if we take the lattices of previous chapters and project them onto two-dimensional surfaces which are neither planar nor cylindrical, then there will be metric distortions: we have to stretch the parastichyParastichy linestransformed lines. As we saw by thinking about increasingly squashed lattices, with fixed divergence d but decreasing rise h, the definition and perception of the principal parastichy numbers depend crucially on the metric properties. The same lattice projected onto two different surfaces will typically have the same sets of generating pairs but the specific pair with the property of being the shortest can change depending on the projection. This is to some extent a mathematical artefact: biologically there is no initial constant-curvature surface of sunflower meristem cells upon which organ commitment actually happens before being rolled into the final shape. In practice, each such ‘lattice point’ is a developmental commitment made at a particular times and geometry of the surrounding tissue micro-environment.